Modern tape measures (or “rule assemblies”) typically include a blade coiled upon a reel that is spring-biased towards a retracted position. A housing generally surrounds and protects the reel with its blade and a retraction spring. The housing includes an opening through which a distal end of the blade extends. Typically, the tape measure housing consists of two housing halves that are joined together by one or more screws. In addition, the housing typically includes a post extending across the midpoint of the housing that provides an anchoring point for one end of the retraction spring, and provides an axle around which the reel may rotate.
In order to conveniently store the tape measure when not in use, a clip is typically provided on the side of the housing and is configured to allow the user to clip the tape measure to his belt. However in some circumstances, for example where the width, and hence the weight, of the tape measure is substantial, a clip on the side of the housing may have the problem that the weight of the tape measure is positioned some distance outward from the point of support, thus allowing the tape measure to rotate downwards to twist off the belt. Some solutions to improved methods for attaching a tape measure to a point of support have been developed, as for example disclosed in U.S. Pat. No. 5,038,985, U.S. Pat. No. 5,388,741, and U.S. Pat. No. 5,450,994.
In another aspect of typical modern tape measures, the fact that the blade is coiled upon a reel by a retraction spring may frequently give rise to problems. First, if the blade is allowed too much movement within the housing as the blade uncoils or recoils, it may have a tendency to become misaligned and hence to become stuck, leaving the blade partway extended from the housing and rendering the tape measure effectively useless. Second, dirt or other foreign matter adhering to the blade may find its way into the housing when the blade is recoiled. This also may cause the reel to jam during retraction. When this occurs, the housing must typically be opened to inspect its interior to determine and resolve the cause of the blockage. However, if it is possible to determine the cause of the blockage without opening the housing, the problem may be solved by means other than opening the housing, such as by pulling out the entire length of the blade and letting it wind back into the housing under control.
Accordingly, there remains a need for improved tape measure housing designs, particularly those that have a more suitable and robust structure for attaching tape measures to the clothing or equipment of a user. There also remains a need for improved tape measure housing designs that permit a user to make a preliminary determination, when the retraction mechanism becomes jammed, as to the cause thereof.